Bias-crosslaying apparatus with mandrel conforming belt

ABSTRACT

An apparatus for bias-crosslaying elongated web material is disclosed. The apparatus includes a stationary mandrel, an endless mandrel conforming belt, a plurality of planetating supply rolls and a slitter. Additional rolls for supplying longitudinally directed inner and outer webs of material are also provided. In the preferred embodiment the edges of the mandrel conforming belt include metallic elements and magnetic means within the mandrel help keep the belt in mandrel conforming configuration. Alternative means for sealing the edges of the material before slitting are also disclosed.

limited Mates Patent [72] Inventor Dean K. Anderson Neenah, Wis. [21] Appl. No. 803,175 [22] Filed Feb. 28, 1969 [45] Patented Oct. 26, 1971 [73] Assignee Kimberly-Clark Corporation Neenah, Wis.

[54] BIAS-CROSSLAYING APPARATUS WITH MANDREL CONFORMING BELT 24 Claims, 12 Drawing Figs.

[52] US. Cl 156/432, 156/426 [51] lnt.Cl B3lc 3/00 [50] Field of Search 156/432, 426; 198/41 [56] References Cited UNITED STATES PATENTS 727,291 5/1903 Clark 198/41 1,601,550 8/1923 Abbott, Jr. 156/426 1,838,529 12/1931 Cochran et al. 198/41 2,748,831 6/1956 Nash 156/432 X 2,841,202 7/1958 Hirschy 156/426 3,132,986 5/1964 Goldman 156/432 X 3,407,107 10/1968 Skoggard et al. 156/432 3,444,020 5/1969 Kalwaites 156/426 X 3,506,522 4/1970 Onifer, Jr. et a1. 156/432 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-G. E. Montone Att0rney-Wolfe, Hubbard, Leydig, Voit & Osann PATENTEUum 26 I971 3,616,062

SHEET u 0F 4 Wye/d BIAS-CROSSLAYING APPARATUS WITH MANDREL CONFORMING BELT BACKGROUND OF THE INVENTION The present invention relates generally to crosslaying apparatus and more particularly concerns apparatus for biascrosslaying elongated web materials.

In forming multiple ply nonwoven products it is often desirable to crosslay various ones of the plies in order to improve the strength of the resulting product. One way to accomplish this is to helically wind the material around the cylindrical section of a stationary mandrel and then pull the helically wound tube of material from the mandrel with a pair of pinch rolls which also flatten the tube material into a biascrosslaid double ply product. Apparatus of this type is dis' closed in copending application Ser. No. 599,766, filed June 23, 1966, in the name of Andrew C. Berry.

It has also been proposed to helically wrap two or more plies of material in opposite directions on a stationary mandrel and then slit, spread and flatten out the resulting bias-crosslaid product. Apparatus of this general type is disclosed in copending application Ser. No. 55,845, filed July 17, 1970 in the names of Anthony S. I-Iubin and Harlan W. Hirschy. That application also discloses an arrangement for adding machine direction plies of material for producing a seamless bias-crosslaid material.

In both of the foregoing types of apparatus at least one ply of the material is applied directly to the surface of the mandrel. Such an arrangement is satisfactory if the ply of material has sufficient strength and stability to withstand the force required to pull the material from the mandrel. However, neither of these arrangements is particularly suited for making material consisting solely of bias-crosslaid webs of light weight, highly drafted, staple length fibers. Such webs have very low machine direction strength and essentially no strength in the cross direction and frequently fail if helically wound directly on apparatus of either of the foregoing types.

SUMMARY OF THE INVENTION Accordingly, the primary aim of the present invention is to provide a bias-crosslaying apparatus which is effective to handle very light weight webs of highly drafted staple length fibers without appreciable danger of web rupture. It is a more particular object to provide such apparatus with an endless mandrel conforming belt for supporting and carrying the web material on the mandrel.

A further object is to provide an apparatus of the above type with magnetic means for assisting in retaining the carrier belt in mandrel conforming configuration.

Another detailed object is to provide means for sealing the crosslaid web material on either side of the longitudinal line along with it is to be subsequently slit.

Other objects and advantages of the invention will become more readily apparent upon reading the following detailed description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a somewhat simplified and diagrammatic side elevation view of the bias-crosslaying apparatus of the present invention;

FIGS. 2 and 3, respectively, are perspective views of the tapered nose and tail segments of the stationary mandrel shown in FIG. 1;

FIG. 4 is an enlarged fragmentary longitudinal section of the mandrel;

FIG. 5 is a section taken along line 5-5 of FIG. 4;

FIG. 6 is an enlarged fragmentary portion of the section seen in FIGS;

FIG. 7 is an enlarged fragmentary longitudinal section of the mandrel showing one form of the sealing and slitting means;

FIG, 8 is a section taken along 88 in FIG. 7;

FIG. 9 is a view of the underside of the mandrel as seen along line 9-9 in FIG. 7;

FIG. 10 is a section taken along line I010 in FIG. 7;

FIG. 11 is a view similar to FIG. 9, showing an alternative edge-sealing arrangement;

FIG. 12 is an enlarged fragmentary cross section of the mandrel showing the alternative edgesealing apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawings, there is shown in FIG. I an illustrative bias-crosslaying apparatus 20 which embodies the features of the present invention. The crosslayer 20 includes an elongated stationary mandrel 21 which is supported above the floor by framing pedestals 22 and 23. A pair of counterrotating carrier rings 24 and 25 are disposed in axially spaced, concentric relation about the mandrel 21. The rings 24, 25 each carry a pair of angled support posts 26 and a pair of guide bars 27 for helically wrapping elongated webs a, b, and d of material from respective supply rolls 28-31 about the mandrel 21. The rings 24, 25 are rotated in opposite directions by a motor 32 operating through a first drive shaft 33, pulley 34 and drive belt 35 and a reverse drive shaft 36, pulley 37 and belt. A pair of reversing gears 38 and 39 interconnect the first and second drive shafts 33 and 36, respectively.

In accordance with the present invention a generally flat, flexible carrier belt 40 is disposed to travel in an endless loop along the length of the mandrel and then return. As it travels over the mandrel 21, the belt is conformed about the mandrel by a concentric guide or fonning collar 41. Preferably, the mandrel 21 is formed with a tapered nose end 42 which merges into a cylindrical mandrel section 43 through a transition zone 44 (see FIG. 2). The width of the belt 40 in the illustrated crosslayer 20 is substantially equal to the circumference of the cylindrical mandrel section 43 and the belt 40 is com formed about the mandrel 21 with the edges of the belt disposed nearly together. At its other end the mandrel is formed with a substantially flat tail end 45 which also merges into the cylindrical mandrel section 43 through a smooth transition zone 46 (see Fig. 3) over which the belt travels to change the belt from mandrel encircling to flat configuration without creating appreciable wrinkling or other distortions.

The belt 40 is pulled over the mandrel 21 and off the tapered tail end 45 by a drive roll 50 driven by a motor 51 through a suitable chain drive 52 or the like. On its return the flattened belt travels around a series of guide rolls 53-57 and adjustable tensioning rolls 58 and 59 to another roll 60 which guides the belt onto the tapered nose end 42 of the mandrel 21.

Pursuant to the present invention, both edges 61 and 62 of the belt 40 in the illustrative machine include metallic elements and magnetic means 63 are located within the mandrel for attracting the metallic elements in order to assist in maintaining the belt in mandrel conforming configuration as it travels over the cylindrical mandrel section 43. As best seen in FIGS. 46 the magnetic means 63 includes a pair of spacedapart rails 64 and 65 disposed within the mandrel and extending adjacent the mandrel periphery substantially parallel to the longitudinal centerline of the mandrel. The rails 64, 65 may be supported within the mandrel 21 by any suitable means; shown here as a plurality of T-bars 67. A plurality of magnets 66 having opposite poles in contact with the respective rails 64, 65 are provided for magnetizing the rails in order to attract the metallic elements located in the edges 61, 62 of the belt 40. While the magnets 66 are shown as being permanent magnets, it will be understood that suitable elec tromagnetic means may also be employed.

To facilitate movement of the belt with its edges 61 and 62 in closely spaced abutting relation an endless support belt 70 is mounted for movement within the mandrel 21 along a closed loop portion of which extends between the magnetic rails 64, 65 and the belt edges 61, 62. The control belt 70 is preferably fabricated out of monmagnetic materials so that the magnetic field imposed on the rails 64, 65 by the magnets 66 draws the belt edges 61. 62 against the lower surface of the belt 70. The belt 70 is trained around rollers 71-74 journaled on cross-shafts 75-78, respectively, within the mandrel. It will be noted that the surface of the mandrel is provided with a longitudinally extending slot 79 in which belt 70 and rails 64, 65 are located. In the preferred apparatus slot 79 extends from adjacent the forward transition zone 44 to adjacent the rear transition zone 46. However it will be appreciated that several axially spaced magnetic rail units and edge holding belts may be disposed between the transition zones 44 and 46, if desired.

As the carrier belt 40 moves over the cylindrical section 43 of the mandrel webs a-d from supply rolls 28-31 are helically wrapped around the moving belt. A cutter in the form of a sharpened wheel 80 is journaled for rotation on a cross shaft 81 such that the edge of the cutter wheel extends peripherally from the mandrel 21 and between the edges 61, 62 of the carrier belt. The cutter is located adjacent the end of the cylindrical mandrel section 43 where it merges into the rear transition zone 46, As shown in FIGS. 1 and the composite web a-d of bias crosslaid material is longitudinally slit by the cutter wheel 80 which cooperates with a rotatable anvil roll 82 journaled by bearings 83 and 84 and driven by a motor 85 through a suitable drive chain 86 or the like.

In keeping with another aspect of the present invention means are provided for adhesively bonding the helically wrapped material in advance of the cutting wheel 80 and adjacent to and on either side of the longitudinal line along with the material is cut. In the preferred embodiment, one or more of the webs a-d include some thermoplastic constituents and the bonding means includes an element 90 for heating the material to activate the thermoplastic constituents. As shown in FIGS. 1 and 7-9 the heating element 90 is a heated roller journaled for rotation about an axis transverse to the centerline of the mandrel and engageable with the helically wound material on the carrier belt 40 along a relatively narrow longitudinal strip indicated at 91. A resiliently covered backup roller 92 isjournaled within the mandrel 21 on a cross-shaft 93 such that the periphery of the backup roll 92 engages and supports the belt edges 61, 62 opposite the heated roller 90.

The thermoplastic constituents in the webs a-d of material may be thermoplastic adhesive or thermoplastic fibers or films. In either case it will be understood that the heated roller 90 is heated to a temperature such that the thermoplastic web constituents are reactivated to achieve the desired degree of bonding along the strip indicated at 91. This serves to stabilize the edges of the composite web a-d after it is slit by the cutting wheel 80 and as it moves over the transition zone 46 of the mandrel. The heated roller 90 may be heated with electric heating elements 94 or with steam or the like.

The present invention further contemplates the application of fresh adhesive to the web prior to slitting when the helically wound webs a d do not include thermoplastic constituents which can be readily activated by heat as discussed above. One such alternative arrangement is shown in FIGS. 11 and 12 and utilizes a pair of adhesive applicators 95 and 96 located on either side of the longitudinal line along which the material is cut and in advance of the cutting wheel 80. Indeed, it is preferred to locate the adhesive applicators 95, 96 between the carrier rings 24 and so that the adhesive may be applied on the outer surface of webs a and b before webs c and d are helically wound over webs a and b. This permits the use of only the minimum amount of adhesive required to bond and thereby stabilize the edges of the composite web.

While the adhesive applicators 95, 96 can take many different forms, those in the alternative embodiment illustrated are a pair of pressurized adhesive guns which discharge discrete spots of adhesive in accordance with timed pulses from a suitable control system (not shown). It will be appreciated however that one or more direct or offset adhesive print rolls could be utilized and that such rolls could be provided with an intaglio pattern in order to apply the adhesive in a spaced pattern, if desired.

After slitting the bias crosslaid material travels with the carrier belt 40 over the transition zone 46 where it is flattened out into continuous sheet form. The material is then carried around the drive roll 50 with the belt and is wound. on a takeup roll 100 with the aid of a peripheral winding roll 101 after the material is stripped from the carrier belt. The winding roll 101 is, of course, driven in timed relation with the carrier belt 21 such as by a chain drive 102 from the same motor 51 that drives the belt 21. Prior to windup, the composite material may be heated by a hot roll 103 cooperating with the drive roll 50 to activate thermoplastic constituents within the webs a-d and calendered by pressure rolls 104 and 105 to improve the adhesive attachment between the respective webs.

It will be understood that webs a and b are helically wound around the carrier belt 21 at a substantial angle, such as 45, to the longitudinal direction of movement of the carrier belt. Webs c and d are then helically wound over webs a and b at a substantial angle such as 90' thereto and such that webs c and d also lay at about a 45angle relative to the belt. After slitting the composite web is flattened out into a bias crosslaid material.

Provision is also made in the crosslayer apparatus 20 to add top and bottom webs of material 'e and f, respectively, which extend in the machine direction. To this end, a supply roll 109 of the bottom web material f is journaled adjacent the nose end 42 of the mandrel and the web material f is guided around a guide bar 110 and over guide roller 60 with the belt 21. The bottom web f thus travels with the belt 21 in mandrel conform ing relation prior to webs a-d being helically wound over web f. The top web e is unwound from a supply roll 111 located adjacent the tail end 45 of the mandrel and around a guide bar 112 into the nip formed by drive roll 50 and drum 103.

Webs a e may all be formed of the same of varying constituents such as, for example, cellulose tissue, carded or drafted fiber webs, plastic flims or some combination of these. By properly selecting the constituents of webs a-d it will be appreciated that a composite web having good strength and stretch characteristics in both the machine direction and cross direction can be obtained. It will further be appreciated that the addition of the top and bottom webs e and f permit the fabrication of a seamless end product.

While the invention has been described and illustrated in connection with certain preferred embodiments and arrangements, there is no intention to limit the invention to those specific embodiments. Rather it is intended to cover all such alternative and equivalent embodiments and arrangements as fall within the spirit and scope of the invention.

I claim as my invention:

1. In an apparatus for bias-crosslaying elongated material, the combination comprising:

a stationary fixed mandrel having an elongated cylindrically shaped center section, a tapered nose, and a longitudinally extending transition zone connecting said tapered nose and said center section;

a generally flat, flexible carrier belt brought into engagement with said mandrel at its nose and along said transition zone, and disposed to travel along said mandrel parallel to its longitudinal axis and return thereby forming an endless loop;

means for moving said belt around said loop;

a guide for conforming said belt over the surface of said cylindrical section as the belt moves along said mandrel, said guide encircling said mandrel at said transition zone;

means for longitudinally feeding elongated web material onto the surface of said carrier belt and through said guide to conform both to said belt and said mandrel over the surface of said cylindrical section of said mandrel;

means for helical wrapping elongated web material around both a longitudinal web and said belt as they move along the center section of said mandrel;

a cutter disposed to cut helically wrapped web material between the edges of a longitudinal web,

and means for separating the composite cut webs from the said carrier belt and for flattening the composite webs into a crosslaid material.

2. The combination defined in claim 1 wherein the width of said belt is substantially equal to the circumference of said cylindrical section of said mandrel and said belt conforms thereto with its edges disposed nearly together.

3. The combination defined in claim 1 wherein said mandrel is formed with a substantially flat tail end which merges into said cylindrical section through a smooth transition zone over which said belt travels to change said belt from mandrel encircling to fiat configuration without appreciable wrinkling and other distortions.

4. The combination defined in claim 1 wherein said cutter is a sharpened wheel journaled for rotation within said mandrel about an axis transverse to said centerline and disposed to extend peripherally from said mandrel and between the edges of 'aid mandrel conforming carrier belt.

5. The combination defined in claim ll including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material adjacent to and on either side of said line along which said material is cut.

6. The combination defined in claim 5 wherein said material includes at least some thermoplastic constituents and said bonding means includes an element for heating said material to activate said thermoplastic constituents.

7. The combination defined in claim 6 wherein said heating element is a heated roller journaled for rotation about an axis transverse to said centerline and having a peripheral portion engageable with said helically wound material on said carrier belt along a relatively narrow longitudinal strip which straddles said cutter.

8. The combination defined in claim 7 including a resiliently covered backup roller journal-ed within said mandrel for rotation about an axis transverse to said centerline and having a peripheral portion engageable with said edges of said belt opposite said heated roller.

9. The combination defined in claim 5 wherein said adhesive bonding means includes an adhesive applicator disposed to apply adhesive on either side of said line to the surface of a first layer of said helically wrapped material prior to a second layer of said material being helically wrapped thereon.

10. The combination defined in claim 1 wherein said helical wrapping means includes counterrotating elements arranged to wrap said material around said mandrel conforming web material on said carrier belt in crossing helical paths and including a second supply roll of elongated web material and means for feeding said second web material onto the surface of said helically wrapped material after the latter material has been cut by said cutter.

ii. The combination defined in claim 1 wherein said web material is guided around said mandrel into substantially completely encircling relation with the edges thereof disposed to pass on opposite sides of said cutter and including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material to said edges.

32. in an apparatus for bias-crosslaying elongated material, the combination comprising:

a stationary fixed mandrel,

a generally flat, flexible carrier belt disposed to travel along said mandrel parallel to its longitudinal axis and return thereby forming an endless loop;

means for moving said belt around said loop;

a guide for conforming said belt over the surface of said cylindrical section as the belt moves along said mandrel, said guide encircling said mandrel; and

means on said mandrel cooperating with means mounted on the edges of the belt for holding said edges in close abutment and for holding the belt in tight conformity to the mandrel throughout its full circumference while said belt travels said center section of said mandrel. H3. The combination defined in claim 12 wherein said holding means includes:

metallic elements disposed along the edges of said belt; and means located within said mandrel for magnetically attractin said metallic elements. 14. he combination defined in claim 13 wherein said magnetically attracting means includes a pair of spaced-apart rails disposed within said mandrel and extending adjacent the periphery thereof substantially parallel to the longitudinal centerline of said mandrel and along which said metallic elements travel.

15. The combination defined in claim 14 including means for magnetizing each of said rails in order to attract said metallic elements.

16. The combination defined in claim 12 including means for helically wrapping elongated material around said carrier belt as it moves over the cylindrical surface of said mandrel and a cutter disposed to cut said helically wrapped material along a line parallel to the longitudinal centerline of said man drel prior to the point at which said carrier belt returns.

17. The combination defined in claim l6 wherein said cutter is a sharpened wheel joumaled for rotation within said mandrel about an axis transverse to said centerline and disposed to extend peripherally from said mandrel and between the edges of said mandrel conforming carrier belt.

18. The combination defined in claim 17 including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material adjacent to and on either side line along which said material is cut.

19 The combination defined in claim 18 wherein said material includes at least some thermoplastic constituents and said bonding means includes a heated roller joumalcd for rotation about an axis transverse to said centerline and having a peripheral portion engageable with said helically wound material on said carrier belt along a relatively narrow longitudinal strip which straddles said cutter.

20. The combination defined in claim 19 including a resiliently covered backup roller joumaled within said mandrel for rotation about an axis transverse to said centerline and having a peripheral portion engageable with the metallic edges of said belt opposite thereof from said heated roller.

21. The combination defined in claim 18 wherein said adhesive bonding means includes an adhesive applicator disposed to apply adhesive on either side of said line to the surface of a first layer of said helically wrapped material prior to a second layer of said material being helically wrapped thereon.

22. The combination defined in claim 12 including a supply roll of elongated web material and means for feeding said web material onto the surface of said carrier belt prior to conforming said belt around said mandrel and in advance of said helical wrapping means.

23. The combination defined in claim 22 wherein said helical wrapping means includes counterrotating elements arranged to wrap said material around said mandrel conforming web material on said carrier belt in crossing helical paths and including a second supply roll of elongated web material and means for feeding said second web material onto the surface of said helically wrapped material after the latter material has been cut by said cutter.

24. The combination defined in claim 13 wherein said mandrel is formed with a tapered nose end which emerges into said cylindrical section through a transition zone and said magnetic attracting means are located downstream of said transition zone.

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2. The combination defined in claim 1 wherein the width of said belt is substantially equal to the circumference of said cylindrical section of said mandrel and said belt conforms thereto with its edges disposed nearly together.
 3. The combination defined in claim 1 wherein said mandrel is formed with a substantially flat tail end which merges into said cylindrical section through a smooth transition zone over which said belt travels to change said belt from mandrel encircling to flat configuration without appreciable wrinkling and other distortions.
 4. The combination defined in claim 1 wherein said cutter is a sharpened wheel journaled for rotation within said mandrel about an axis transverse to said centerline and disposed to extend peripherally from said mandrel and between the edges of said mandrel conforming carrier belt.
 5. The combination defined in claim 1 including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material adjacent to and on either side of said line along which said material is cut.
 6. The combination defined in claim 5 wherein said material includes at least some thermoplastic constituents and said bonding means includes an element for heating said material to activate said thermoplastic constituents.
 7. The combination defined in claim 6 wherein said heating element is a heated roller journaled for rotation about an axis transverse to said centerline and having a peripheral portion engageable with said helically wound material on said carrier belt along a relatively narrow longitudinal strip which straddles said cutter.
 8. The combination defined in claim 7 including a resiliently covered backup roller journaled within said mandrel for rotation about an axis transverse to said centerline and having a peripheral portion engageable with the edges of sAid belt opposite said heated roller.
 9. The combination defined in claim 5 wherein said adhesive bonding means includes an adhesive applicator disposed to apply adhesive on either side of said line to the surface of a first layer of said helically wrapped material prior to a second layer of said material being helically wrapped thereon.
 10. The combination defined in claim 1 wherein said helical wrapping means includes counterrotating elements arranged to wrap said material around said mandrel conforming web material on said carrier belt in crossing helical paths and including a second supply roll of elongated web material and means for feeding said second web material onto the surface of said helically wrapped material after the latter material has been cut by said cutter.
 11. The combination defined in claim 1 wherein said web material is guided around said mandrel into substantially completely encircling relation with the edges thereof disposed to pass on opposite sides of said cutter and including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material to said edges.
 12. In an apparatus for bias-crosslaying elongated material, the combination comprising: a stationary fixed mandrel, a generally flat, flexible carrier belt disposed to travel along said mandrel parallel to its longitudinal axis and return thereby forming an endless loop; means for moving said belt around said loop; a guide for conforming said belt over the surface of said cylindrical section as the belt moves along said mandrel, said guide encircling said mandrel; and means on said mandrel cooperating with means mounted on the edges of the belt for holding said edges in close abutment and for holding the belt in tight conformity to the mandrel throughout its full circumference while said belt travels said center section of said mandrel.
 13. The combination defined in claim 12 wherein said holding means includes: metallic elements disposed along the edges of said belt; and means located within said mandrel for magnetically attracting said metallic elements.
 14. The combination defined in claim 13 wherein said magnetically attracting means includes a pair of spaced-apart rails disposed within said mandrel and extending adjacent the periphery thereof substantially parallel to the longitudinal centerline of said mandrel and along which said metallic elements travel.
 15. The combination defined in claim 14 including means for magnetizing each of said rails in order to attract said metallic elements.
 16. The combination defined in claim 12 including means for helically wrapping elongated material around said carrier belt as it moves over the cylindrical surface of said mandrel and a cutter disposed to cut said helically wrapped material along a line parallel to the longitudinal centerline of said mandrel prior to the point at which said carrier belt returns.
 17. The combination defined in claim 16 wherein said cutter is a sharpened wheel journaled for rotation within said mandrel about an axis transverse to said centerline and disposed to extend peripherally from said mandrel and between the edges of said mandrel conforming carrier belt.
 18. The combination defined in claim 17 including means located in advance of said cutter and substantially in longitudinal alignment therewith for adhesively bonding said helically wrapped material adjacent to and on either side of said line along which said material is cut.
 19. The combination defined in claim 18 wherein said material includes at least some thermoplastic constituents and said bonding means includes a heated roller journaled for rotation about an axis transverse to said centerline and having a peripheral portion engageable with said helically wound material on said carrier belt along a relatively narrow longitudinal strip which straddles said cutter.
 20. The combination defined in Claim 19 including a resiliently covered backup roller journaled within said mandrel for rotation about an axis transverse to said centerline and having a peripheral portion engageable with the metallic edges of said belt opposite thereof from said heated roller.
 21. The combination defined in claim 18 wherein said adhesive bonding means includes an adhesive applicator disposed to apply adhesive on either side of said line to the surface of a first layer of said helically wrapped material prior to a second layer of said material being helically wrapped thereon.
 22. The combination defined in claim 12 including a supply roll of elongated web material and means for feeding said web material onto the surface of said carrier belt prior to conforming said belt around said mandrel and in advance of said helical wrapping means.
 23. The combination defined in claim 22 wherein said helical wrapping means includes counterrotating elements arranged to wrap said material around said mandrel conforming web material on said carrier belt in crossing helical paths and including a second supply roll of elongated web material and means for feeding said second web material onto the surface of said helically wrapped material after the latter material has been cut by said cutter.
 24. The combination defined in claim 13 wherein said mandrel is formed with a tapered nose end which merges into said cylindrical section through a transition zone and said magnetic attracting means are located downstream of said transition zone. 